Acoustical mine firing control system



G. N. wlLLls 3,016,013

ACOUSTICAL MINE FIRING CONTROL SYSTEM 5 Sheets-Sheet 1 Jan. 9, 1962 Filed Jan. 19, 1945 xbbbbb.

lume/whom G. N. WILLIS Jan. 9, 1962 G. N. WILLIS 3,016,013

ACOUSTICAL MINE FIRING CONTROL SYSTEM Filed Jan. 19, 1945 5 Sheets-Sheet 2 48 IWI" IIIIU Jan. 9, 1962 G. N. wlLLls 3,016,013

ACOUSTICAL MINE FIRING CONTROL SYSTEM Filed Jan. 19, 1945 3 Sheets-Sheet 3 United States Pater 3,016,013 Patented Jan. 9, 1962 Y3,016,013 Y, ACOUSTICAL MINE FuuNG CONTROL SYSTEM Grant N. Willis, washington, no. Filed Jan. 19, 194s,ser.No. 573,621.

i 13 Claims. (Cl. IGZ-48). (Grantednnder Title 35, U.S. Code (1952), sec. 266) VThis invention relates" to mine tiring controlsystems andy more particularly Yto an acoustic minefring control system for underwater mines wherein the system operates to detonate and explode'themine associated therewith when vibrations or pulsations of a predetermined character are Vtransmitted through the surrounding water from sound emitting bodies such as surface Vessels, submarines, or the like, and the system operatesto prevent a firing of the. mine `when heavy explosive charges, such as those employed in counterrnning operations, are exploded fwithin the vicinity thereof. I 7;

In certain o f the prior art systems, electric contact actuating apparatus comprising a plurality of contacts is employed wherein a rst pair of the contacts is adapted to be actuated by sound waves or pulses of predetermined character such, for example, as those produced by a vessel, thereby to control the operation of a mine ring circuit, and a second pair of the contacts'is adapted to be actuated by sound waves or pulses of dilerent character such, for example, as explosion waves, thereby to prevent the first pair of contacts from controlling the firing circuit when such different sound Waves or signals are received. Thus, by this arrangement, a certain measure of protection or discrimination against such sound waves or signals is provided. In accordance with such an arrangement, a time delay device is usually employed to continue the control provided by the second pair of contacts for a predetermined interval of time, thereby to render the tiring circuit inoperative until the aforesaid different signals have'died out in theT acoustic iield or zone of receptivity of the mine.

In certainv of the other prior art systems, microtelephonic devices are employed to initiate the operation of intermediate devices adapted gradually to close a mine tiring circuit in response to signals received from a vessel adapted to be destroyed by the mine employing the system. By reason of the gradual action in closing the mine firing circuit, the system is caused to begin its operation while the vessel is at a relatively great distance from the mine, thereby to re the mine only after a period of time sufhcient to bring the vessel close enough tothe mine to destroy or elfectively damage the vessel. Such an arrangement affords a further advantage in that it precludes a firing of the mine by the explosion of shells ,or bombs in 'its vicinity, sound waves or pulses caused by such explosions being momentary Vonly and therefore too brief to effect a ring actuation of the system. I A

In the arrangement' of the present invention, an acoustic mine lring control system is provided which possesses all of the advantages of the prior art systems and in addition provides a system fwherein certain circuit elements are chosen and arranged in such manner as to provide a relatively highdegree of control of the operation of the Y pulsations of predetermined character and thereby cause system in response to signals of predetermined character the vibrations or pulsations to be converted into electrical signals corresponding thereto. A condenser is connected .tothe control element of a trigger type tube and is adapted to be charged by the electrical signals, whereby the tube is caused to break down and eifect the discharge of a normally charged condenser through a shipcounter or an electro responsive detonating device, as the case may be. A second pair of contacts on the sound responsive device are adapted to be closed in response to a countermine shock received thereby, whereupon aV second trigger type tube is caused to break down and effect a discharge of the normally charged condenser therethrough, thus sterilizing the system for apredetermined period of time corresponding to the time required to recharge the normally charged condenser.

According to the mine firing control system of the instant invention, the elements or component parts thereof comprise static or non-moving parts such, for example, as condensers, resistors and electron discharge devices, which elements are not susceptible to damage caused by shocks associated with the launching of a mine. Accordingly the system of the present invention is well adapted for use in connection with mines adapted to be planted from an aircraft in ight. l

An object of this invention is to provide a new and .improved acoustic mine firing control system which operates in response to signals of a predetermined character to` actuate a mine ring control circuit and operates in response to signals of a different character to prevent the operation of such a circuit. y

Another of the objects is the provision of a new Vand improved acoustic mine tiring control system for a marine mine adapted to fire the mine when a predetermined number of series of vibrational signals has been received through the sourrounding water corresponding to the movement of a predetermined number of vessels past the mine.

Another object is the provision of a new and improved acoustic mine firing control system for an underwater ground mine in which means are provided for effecting a predetermined number of counting operations, corresponding to a predetermined number of vessels moving past the mine, which operations are substantially independent of the time of travel of each of the vessels past the mine.

Another object in an acoustic mine firing control system is the provision of new and improved means responsive to countermining shocks and adapted to sterilize the system for a predetermined period of time.

Another object is the provision of a new and improved Vacoustic mine ring control system in which the vtiring of the mine in response to sound signals of a predetermined character receivedthereby is delayed for a predetermined period of time.

Another object is the provision of a new and improved acoustic mine tiring control system which operates in response to signals of a predetermined character to actu'- ate a mine firing Vcontrol circuit and which provides means for preventing an actuation of the Vmine firing control circuit when signals of a predetermined character and of a different character are received concurrently thereby.

Still another object of this invention is to provide an acoustic mine liring control system for a marine mine in which the system operates to produce a firing actuation thereof only in response to signal frequencies which are within a predetermined frequency band.

Still another object of this invention is to provide a new and improved acoustic mine tiring control system for a marine mine in which the system operates to produce peatedly during the travel of the ship past the mine with.-

out additionally operating the shipcounter.

A still further object is the provision of an acoustic minefring control system which is rugged in construction, economical to manufacture and reliable in service:

Additional objects and advantages, not specifically 'set forth'heretofore, are implied or are inherent in the novel construction, combination-and arrangement of the elements comprising the invention and will become more clearly apparentl as the description proceeds, reference being had to the accompanying drawings wherein:

FIG. l is a sectional View with certain parts in elevation of anunderwater ground mine suitable for use with the. instant invention;

FIG. 2'is a sectional View of the device of the present invention;

FIG. 3 -is a view, partially broken away and partially in section, taken substantially along the line 3-3 of FIG. 2; f

FIG. 4 is a view, partially broken away and partially in section, taken substantially along the line 4-4 of FIG. 3;

FIG. 5 is a view in section taken substantially along the line 5-5 of FIG. 4;

-FIGuisa view, partially broken away and partially in section, taken substantially along the line 6 6 of FIG. 4;

FIG. y7 is a sectional view taken substantially along the line 7-7 of PIG. 4; and 1 4 detonator into operative engagement with the booster charge when the mine reaches a predetermined depth of submergence in `the water, as is well known in the art to which the invention appertains.

the duct 17 to the reduced endi portion of the casing 11.

Arranged within the well 16 in watertight relation therewith, is a clock mechanism 29v adapted to complete certain circuits of lthe electrical system within predetermined intervals of time after-the mine has been launched within the water, as will morer clearly appear as the description-proceeds. For this purpose, a lmulti-conductor cable 31 connected to contacts comprising the clock mechanism Yis extended throughthe duct 18 into the reduced end portion of the casing.v

The well 14 servesas a housing and supportfor a battery, hereinafter referred to as BA, the -battery being clamped within the housing againsta resilient support 32 therein by means of a retaining ring 33 secured tothe bulkheadas by a plurality of studs 34. The battery BA is arranged to supply electrical energy to a tiring control FIG.'8 shows in diagrammatic form a complete system suitablerfor usewith the mine of FIG. Al.

Referring nowto the drawings for a more complete understanding of the invention, wherein like reference characters referto like parts throughout the several views, and more-particularly to FIG. l thereof, the numeral 10Y generally designates an underwater mine adapted to be planted from an aircraft in flight .and adapted tocome'to rest.- on the bed of a body of water in which the mine is-planted. The mine comprises an outercasingll generally of cylindrical .configuration and having a reduced end portion to which iins 12 Vor the like are secured to steer or guide the mine in flight.

The-casing -11 is divided internally at the reduced end portionrthereof lby a bulkhead `13 which supports a well 14 for a purpose hereinafter disclosed. The casing .111 is also .provided with inwardly extending -wells 15 and v16 from which extend respectively, tubes or ducts 17 Yand-.1Std` the bulkhead 13. The casing is further provided witha wel-l. 19 in which a percussion detonator may be inserted, if desired, when' the mine d0 is to be usedforpurposes other than those disclosed herein. Accordingly, for purposes herein disclosed,V the well 19 is `sealed as by Atheplug 21.

The remaining space within the main portion of the casing 11 is lled with an explosive fcharge 22 of TNT 'orthe like-sufficient to destroy or damage a vessel and to imparta negative degree of buoyancy to the mine whereby the mine is caused to sink through the water and come to rest on the bed thereof. The explosive charge conveniently may be admitted into the casing by way of a suitable watertight filler opening 23.

A booster charge 24 and the extender mechanism 25 usually associated therewith are arranged within the well 1S in water-tight relation therein. The extender mechanism carries an electro-responsive detonator 26 for ig- `niting the -booster` charge I24 and is adapted 'to move the mechanism 35 by -way of a multi-conductor cable 36 when the aforesaid certain circuits have been closed by the clockrmechanism 29 as explained in the foregoing.

The mechanism'35 is supported on the studs 34 by means-of a plurality of flexible spacer plates 37, which plates may ybe formed of any suitable `material such, for example, as wood, the platesbeing supported on the studs and shaped to conform` to the end-portions of the mechanism. The free end portions of the studs 35 extend through and are supported A-by the-plate 38, which plate is shaped to conform slideably with the inner lsurface of the casing 11. The projecting portions of the studs are threaded to receive a plurality of nuts 39 whereby the mechanism 35 may be clamped between thel plates 37 when the nuts are-drawn up tight-against the slideable plate 38, substantially as-shown.

The reduced end portion of the ymine casing, at the` `open end thereof, carries a ring memberv -41 which is secured to the casing as by welding or otherwise suitably secured thereto. A dish-shaped-cover 342 is-secured to the member 411 in watertight relation therewith as by a j plurality of screws 43 ycarried by the angeportion 44 of the cover. The cover is provided with a central opening for receivingra sound responsive device-46 hereinafter referred to as an acoustic tickler. The device 46 is provided with a circular base 47 by meansof ywhich the devi-ecris secured, as by .a pluralityl of lscrews 48, to the cover, a suitable lgasket 49 beingfinserted between thecover and the base 'to insurefa watertight connection therebetween. f

The sound responsivedevice or tickler 46 is shown in greater detail in FIGS. 2 through" 7, the4 device comprising a support 51 secured to a'circular'basef47 asby a plurality of screws '521.V Also-secured to the base 47 is a casing 53 for the device, which casing is .provided with a circular tlanged portion 5'4 having'a plurality of holes therein adapted. to receive .the'fscrews-48. A thin flexible daphragm 56, preferably circular in shape and of a material suitable for the purpose such, yfor example,v as beryllium copper orsheet metal, isgmountedA between the .base 47 and the supporting member 51.v Thebase 47 is provided with a recessed aperture 55 which/allows pulsations or vibrations.receivedthrough an elastic-medium to react upon the surface of the diaphragm. f

The `diaphragm 56 and support 51 .are provided with coincident apertures within ywhich isdisposed a post 57 securely. clamped tothe diaphragm byfmeanszof' a packing nut 58 screwed to a threaded extremity'of the post 57 whereby oscillation of the. diaphragmcauses the post to oscillate. A suitable: gasket 59 is arranged -zbetween the packing nut and Ydiaphragm to insure; a ywatertight relation therebetween.

Secured .to the. supporting Vmember 51-.by means of the screws 64.are1the mounting strips :61,62 and.63,. each The -leads 27 of the detonator comprise a cable 28, which is extended through being electrically insulated from the otherv by aI strip of suitable insulating material 65 such, for example, as

rubber, Bakelite or the like, the strip 63 also being inf sulated from the Vsupport 51 by an additional strip of similar insulating material. The mounting strip 63 has two upright portions 66 and 67', the portion 66 having a threaded hole therein adapted toA receive the adjustable screw bearing 68, the portion 67 also being provided with a threaded hole therein adapted to receive the screw bearing 69. A nut 71 is provided-upon the bearing 69 for maintaining thebearing in an adjusted positionl with respect to the upright portion 67. Disposed about the adjustable screw bearing 68 is an internally bored circular is a resilient spring 74 known in the trade as a hair spring, having the other end thereof in engagement with the shaft 75. The screw 68" is provided with a tapped hole concentric with the aXis of the screws 68 and 69 by means of which the shaft 75 is mounted for rotation about the axis. The balance wheel 76 is secured to the shaft 7S and rotatable therewith, the balance wheel being provided with an electrical contact 77 adapted to engage contact 78 aixed to the post 57 and be stopped thereby Awhen the device is in a state of rest, the pressure between the contacts 77' and 78' being maintained at a predetermined value by the tension of the hair spring 74 in accordance with the setting of the member 81.

The mounting strip 62 has an electrical contact 82 extending therefrom adapted to be engaged by the contact 77 aixed to the balance wheel when the pressure signal acting upon the diaphragm 56 is of suliicient` magnitude. The conductor 83 is soldered to the post 57 thereby maintaining the conductor in electrical connection with contact 78. Similarly, conductor 84 is soldered to the mount-w,

ing strip 61, thereby maintaining conductor 84 in elec-- trical connection with contact 77; while conductor 85 is xed to the mounting strip 62 thus maintaining con- ,ductor 85 in electrical connection with` contact 82.

A suitable cup-shaped cover 86 is secured to the support 51 by a plurality of screws 87, the cover having arranged therein a partition y88 with a flanged portion 89 provided with a hole which is adaptedto receive the post 57. In the bottom of the cover are a plurality of holes through which the conductors 8'3, 84 and 85 are passed, with encasing means 91 being provided for each conductor to prevent water from seeping into the cover. A suitable gasket 92I is mounted between the cover 86 and support 51, thereby insuring a watertight connection therebetween.

The device is also provided with a rubber sack 93 arranged within the casing 53, the sack being securely clamped between the vbase 47 and the flange portion 54. Cut into the flanged portion 54 is a port 94 which allows water to pass into the space between the casing 53 and the sack 93, therebydeating the sack and causing the air therein to be compressed. A hole 95 in the cover 86 also allows the air within the cover to be compressed and by reason of a plurality of holes 135 Vcut in the support 51 the resulting air pressure is applied to the surface of the diaphragm 56 against the support, thereby substantially equalizing the total pressure applied to the diaphragm when the device is immersed in a body of water. A housing 96 is secured to the casing 53, the housing having holes cutin its top and `bottom surfaces through which the cable 97, containing conductors 83, 84 and 85, is passed. A plurality of holes arealso cut in the casing 53 to allow passage therethrough of the conductors 83, 84 and 85, with suitable encasing means being pro- .videdat each hole in the casing '3 and housing96 to prevent leakage of water into the ldevice 46 and also to Vprevent air from escaping the device.

A short description of the operation of the sound responsive device 46 will now be given. Let it be assumed by way of example that the mine 10 has been'launched in a body of water and has come to rest on the bed thereof, its position being adjacent the path of travel of an approaching vessel and that the mine is in an armed condition. The diaphragm 56 is now subject to the pressure of-,the surrounding water and in order to compensate -for this, water iiows into the port 94, thereby causing the rubber sack 93 to partially co1lapse. When this occurs, air contained in the casing 53= and inthe cover 56 is compressed sufficiently to substantially Vequalize the pressure acting on the Asurface of the diaphragm which is in contact with the surrounding water.

As is well known in the art to which the invention appertains, it has been found that a considerable range of frequencies is transmitted by the propeller of a ship in motion. 'I'he system of the present invention has been designed to operate on a frequency band included within vthe sonic range of frequencies generated by the ships propeller.

The sound intensity received through the water is ,of a relatively small value in the area ahead of the ship as the ship is propelled through the water, increasing somewhat as the bow of the ship passes the mine and thereafter increasing progressively until the ships propeller is above the mine. The acoustic device included in the system of the present invention is adjusted to operate on the strength or intensity of signals received from theships propeller corresponding generally to the intensity of signals detected beneath the forward or amidship portion of the vessel, such adjustment being made by a change in the pressure between the contacts 77 and 7S resulting from the rotation of the ring member 81, FIG. 6. Y f

Wherrsuch a signal is received, the diaphragm 56 vvibrates sufficiently to cause fthe post 57 secured to the diaphragm to oscillare. When this occurs, the contact- 77, securedto the balance wheel 76, is alternately moved away from and, by reason of the resilient spring 74, moved into engagement with contact 78 associated with the post 57, thereby 'alternately opening and closing a.

circuit comprising the contacts 77 and 7 8. Y

In the event a heavy explosion such, for example, as that associated with countermining operations, occurs within the vicinity of the mine, the diaphragm 56 and post 57 vibrate su'iciently to cause the Contact 77 to be momentarily moved into engagement with contact 82 secured to the mounting strip 62, thereby closing a circuit comprising the contacts 77 and y82, the resilient spring 74 thereafter restoring the contact 77 to its initial position into engagement with contact 78.

In view of the foregoing, it is apparent that the tiring operation of the system is dependent upon the amplitude or intensity of sound signals within a predetermined band of frequencies corresponding approximately to fthe resonant frequency of the tickler for the reason that the tickler cannot be caused to operate in response to signals of -a frequency outside such band notwithstanding that the amplitude of such signals exceeds Vthat requiredby a particular 'adjustment of the ltickler to set the same in operation. A

However, if the amplitude is extremely large, as in 'the case of signals due to countermine shocks, the tickler ytiring control circuit including the heretofore described sound responsive device, suitable for use in the mine of cession in response Ito' thepassagel of a'plurality of ves?VV sels .movingin succession past the mine, is operatively connected-to the normally charged condenser C1, and is adaptedxtobe:operatedfby thelcondenser C1, when-it disl charges. ThecondenserCZisconnected to the control grid V1113 of.: the firing tube 99 and prevents a rap-idV increase of potentialof vthe control grid as the acoustic tickler 46 operates suiciently to disenga-ge theA normally closed kcontacts 77 and 78.

The circuit also comprises an arming clock A suitable for the purpose such, for example, as the mechanism described and claimed inthe copending application of lJames B; Glennonet al. for Firing Mechanism for a Submarine Mine, Serial No. 395,230, tiled May 26, 1941. As is Well known in the art to which the inventionappertains, the

arming clock A is adapted to complete 'a plurality of circuits in predetermined'sequential order when a predetermined 'period of time has. elapsed after the launching olf the mine.

The operation of the system of the instant invention willl now be described with particular reference to FIG. 8 of the drawings. Let it be assumed that the mine 10 has been launched into a body of water-and has come to rest on the bed thereof. Let it further be assumed that theextender mechanism 25 has operated and moved the detonator 26 into operative relation with the booster charge 24. Y

After an interval of time has elapsed during which Va salt Washer comprising `an element of the clock rnechanism A, FIGfS, is dissolved, a diaphragmV 10S comprising another element of the clock mechanism is permitted to move under pressure of the surrounding water and to initiate the operation of a spring wound motor, which motor drives cam 1116 of the clock mechanism a predetenmined distance. While the cam 106 is rotating, contact spring 107 is moved into engagement with contact spring 108, thereby completing a circuit from the electroresponsive detonator 1019 to the ship counter indicated generally by the numeral 111. As the cam 10'6 continues to rotate, the-contact spring 112 is moved into engagement with contact spring 113, after which the cam ceases to rotate. When contact spring 112 engages contact spring 113 -a circuit is completed from the positive terminal of battery BA overa conductor 114, contactsprings 113 and 112 of the clock A, conductor 115, resistor R1, conductor 116 and thence to the plates 101 of the trigger tubes 98 and 99, thereby applying a plate potential to each one of the tubes of a value controlled by the maghi; tude ofthe resistor R1 and the current caused to ow `therethrough by the voltage output vof battery BA. l

A potential lis also applied to the control grids 10S-of the tubes 98 and 99 when contact spring 112 engages contact-,springs l'113 vand 112, conductor l115, resistor R1,

-thepositive terminal of battery BA over conductor 114, contact springs 13 and 112, conductor 1715, resistor R1,

conductor '116,V resistor R4 and thence to the control grid 103 of tube 99; the circuit of the tube 98'continuing from the resistor R4 over conductor 117, contacts 78 and 7.7, acoustic tickler 46, conductor 118, resistor R6 and thence to the grid V103 of tube 98. The value of the potential appliedto the grids 103 oftubes 98 and 99 is controlled by the values of the resistors R1, R2, R3, R4, `and R5, the resistors' being connected in series across battery BA, to form Ia voltage divider, and the control grids103 are connected electrically to the samepoint on the divider,

thereby causing thevoltages appliedto the .gridl ofeach tubeto be substantially equal and to he `substantially lone third ofthe voltage applied to the plates 101v of the-tubes.

Concurrentlylwith the closure of contacts 112. and 113 of the arming clock A, condenser C1, charges tothe output r`voltage of battery BA `minus the potential drops Iacross the resistors R1 and R5, a circuit beingclosed l fromthe ,postive terminal of battery BA overconductor 114, contacts 113 and 1120i arming clock A,y conductor 115, resistor'` R1, conductor 116, condenser C1, conductor 119, resistor R5,.conductor 121-, from whence the circuit is completed to the negative terminal of battery BA. It Willsbe understood that during the charging period of condenser C1, a small value of current ows from'the positive terminal of battery BA over conductor 114, contacts 113 and 112 of the arming clock A, conductor 115, resistor R1, conductor 116, resistor R4, conductor 117, condenser C2, conductor 121, from whence the circuit is completedto the negative terminal of batteryvBA, thereby causing the condenser C2 to become charged to the normal grid potential of the tubes.

When an enemy vessel moves into proximaterelation with respect tothe acoustic tickler 46, the vibrations caused by the ships propeller and transmitted through the surrounding Water cause the 'contact 77l of the tickler 46 to be movedaway from. the contact 78- thereof, as heretofore described. `When this occurs, the charge on the condenser C2 is caused toincrease by reason of the resistors R2 and R3 being cut from the voltage divider circuit. The condenser C2 obtains this increase in charge over Athe following circuit; positive terminal of battery BA, conductor 114, contacts 1,13 and 112 of the arming clock A', conductor 115, resistor R1, conductor 116, resistor R4, conductor `117, condenser'CZ, conductor 121 and `thence to the negative terminal of battery BA, thereby Vincreasing the poten-tial at the point 122, Vwhich potential is appliedto the grid 103 lof the tiring tube 99. However, the tubev 99 is not fired at this time -for the reasonthat the potential at the point 122vis noty suicient Y 103 of tube '99, whereby the tube is caused'to're. When this occurs, the. normally charged condenser C1 discharges over the followingpath; positive plate of condenser C1, conductor 116, through the ltube 99,'conductor 121, the fusible; element 123 ofthe ship counter 111, conductor 119and ythence to thenegative plate of'condenser C1, thereby melting the element 123 of the shipcounter, and causing the. spring contactelement 124 associated therewith to move into engagement with the plate contact 125 of the second fusible element 126.

As the firing tube 99is red, the voltage at the point 127 `in the circuit, which i-s lthe Vvoltage applied to the condenser C1and to theplate 101 ofvthe -tube 99, is decreased below that ofthe maingapsustaining voltage of the tube, by reason of thevresistor R5, which is of low value and connected between/conductors 119 and `121 therebyextinguishing the tube. Furthermore, when the tube is firing the condenser C2 loses some of, its charge over the following path; positive plate of ,condenser'CZ, conductor 117, control grid 103.and cathode 102 of'tube 99,`conductor 121Qand thence to the negative plate of condenser C2, thereby reducing the potential of the point 122 in the circuit.

The voltage on the normally charged condenser C1 now vstarts to build up lover its charging circuit and the charge on condenser C2 .also builds up over its charging circuit in` response to the continuous vibration of contact 77 ofthe tickler.46. The condenser C2 will reach the tiring -bias and when the voltage -at point i127 increases ,to approximately twothirdsof the volt-age output of batv to be incapable of causing disengagement of the contacts 77 and 78 of thetickler 46, thereby preventing the potential at 122V from building up to the necessary tiring bias for the tube99. When this occurs, the condenser O1 is again charged to substantially the potential of battery BA and the charge on condenser C2 is restored to its normal potential insuilcient to lire the tube 99. The system is now inrreadiness to respond to the next vessel which passes above or near the mine.

In a similar manner, the next succeeding eight fusible As the condenser This cycle of operations is repeated=until theV resistor R2 and condenser C2 are such that the system will normally respond to the passage of va vessel over the mine, substantially independent of the speed with which the .vessel moves past the mine. |If a vesselis moving rap-v idly, the short time constants provided. allowv condenser lC2 to charge suiciently to re tube 99 and discharge condenserCl through the shipcounter. When tube 99 is exl tinguished, the chargeson both condensers n'se concurrently, the interval of time required being relatively short,

thereby rapidly adjusting the system to be in readiness to respond to the next succeeding vessel passing over the elements are destroyed in response to vibrations detected by the acoustic tickler from the next eight succeeding vessels to pass over the mine. The detonator 109 is now included in the discharge path of condenser C1, since the operation of the last remaining fusible element 134 in the shipcounter 111 will cause the detonator 109 Vto be tired 4by the remaining discharge current from the condenser C1.

As the tickler vibrates in response to the passage of theV tenth vessel Aover the mine, the potential at 122 increases to the tiring Ibias of tube 99 andthe tube hres. When thi-s occurs, the condenser C1 discharges over the following path; positive plate of condenser C1, lconductor 116, plate 101, grid 103 and cathode 102 of tube 99, conductor 121', fusible element 134, conductor 119 and thence to the negative plate of condenser C1, the remaining discharge current from C1 continuing from fusible element 134 over conductor 128, electro-responsive ,detona-ting device 109, conductor 129, contacts 108 and 107 of arming clock A, conductor 181,` conductor 119 and thence to the negative plate of condenser C1, thereby firing the mine beneath a`-vulnerable portion of the tenth i vessel to pass over the mine, x

In the event that a countermine signal is received,

Acontact 77 of the acoustic tickler46 moves into engagement with Contact 82 thereof, whereupon the voltage applied to the plates 101 of the tubes 98 and 99 also Vapplied to the control grid 103 of the 4tube 98 through the contacts 77 and 82 of the tickler and conductor118, thereby causing the tube 98 to fire. When this occurs, the normally charged condenser C1 discharges over the following path; positive plate of condenser C1, conductor v `116, plate 101, `grid 103 and cathode 102 of tube 98,

C1 begins to-recharge through resistor R1 to its initial value, sterilization of the circuit con-tinuing'until C1 obtains its initial charge. It will be understoodf at this point that the ringtube 9.9 is not tired as a countermine signal is received -by reason of the Vtime required to raise ,the voltage of condenser C2 sufficiently to fire the tube.

Moreover, when tube 98 is extinguished, the potential applied to theplate 101 of tube'99 decreasesconcurrently with the decrease in the pla-te potential of tube 98, thereby further insuring that tube 99 will not re in response to a counterminegsignal.

It will be noted that the timeconstants associated with the RC combination of resistor R1 and condenser C1 and lf a vessel moves slowly past the mine, ,ther condenser C2 obtains suicient charge to cause tube, 99 to tire as the vessel reaches a point directly over the mine, thereby causing C1 to discharge through the shipcounter. As the vessel slowly moves away from the mine, the charges on condensers C1 'and C2 rise concurrently, the condenser C2 being adapted to discharge and charge repeatedly with- Vout additionally operating the shipcounter if the sound sigials received by the tickler are of a predetermined character, adapted to cause condenser C2 to obtain a charge sufdcient to fire tube 99. An arrangement is thus provided whereby the system is adapted to operate satisfactorily ,in response to the passage of a wide variety of vessels over the mine at various speeds.- i

It will be understood that the sensitivity of the system Amay be varied in two ways. Rotation of the ring member 81v varies the pressure between the normally closedcontacts 77 and '78 and thereby the response of the tickler 46 to the intensity of vibrations or pulsations transmitted through the surrounding water is increasedl or decreased in accordance with the direction of rotation of the member 81. Morever, by changing the valueof capacitance of the condenser C2, the interval of time required to increase the voltage applied to the grid 103 of tube 99 suiiiciently to re the tube may be varied in accordance with an increase or decrease in the capacity of C2.

In a specific circuit, the following values of circuit con-V Vthe plates 101 of the trigger tubes 98 and 99 is 135 volts,

a voltage equal to or greater than the main gap sustaining voltage for the type of cold cathode tube employed herein. In accordance with the values of the resistors Rl---RS which form a voltage divider circuit, the initial potential existing at the points 122 and 133` in the circuit is onethird that of the plate voltage, hence 42 volts, this voltage being ysubstantially less than the tiring bias of these tubes. The grids 103 of both the tubes 98 and 99 are connected to the same point in the voltage idivider circuits, which point embraces the resistor R3,'1 megohm; R2, 5 ohms and R5, also 5 ohms. The remaining resistors R1, 0.5 megohm and R4, 2 megohms, constitute approximately two-thirds the total resistance in the divided circuit. Values of capacity of the condensersCl and C2 which have produced satisfactory time Vintervals are 125 microfarads and 0.5 miorofarad, respectively. The resistor R6, 10,000. ohms, is provided in the grid circuit of tube 98 in g order to protect thetube from high currents while the tube is ring. Thus, substantially no current flows through resistor R6 whereby a negligible voltage drop appears thereacross and the voltages at the grids of the tubes 98 and 99 normally are vsubstantially equal.

Briey stated in summary, the instant invention contemplatesy ajnew and improvedV acoustically controlled mine ring system, wherein an acoustic tickler is adapted to selectively control the operationof a pair of electron discharge devices, which devices turn selectively control the` discharge path'of an-electrolytic condenser in accord- 1 ance with the character of signals detected by the tickler.

While the invention has been described with particular il reference toan example thereof which gives satisfactory results, it will be readily apparent to those skilled in the -art to which the invention appertains, after understanding the invention herein described, thatfurther embodiments, modications and changes of the invention may be made without departing from the spirit and scope thereof, as defined by the claims appended hereto.l n A' The invention herein described and claimed may be manufactured and used by or for the Government of the f United StatesV of America without payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters-Patent of the United States is: Y

l. In anacoustically controlled marine mine adapted to-be tired in response to sound signals received from an approaching vessel, a sound responsive device adapted to be set into operation as the vessel enters the threshold of sensitivity of the mine, a source of electrical energy, a discharge path for said source of energy, detonating means included in said discharge path and adapted to be red as energy flows in the path, -an electrical energy storage device, means including said sound responsive device for causing energy from said source to be stored periodically in said energy storage device as `the sound responsive device operates and time measuring means controlled by said sound responsive device and including said-energy storage device for causing energy to ow through said path when a predetermined period of time has kbeen meas'- ured by the time measuring means in response to continuous operation of the sound responsive device.

2. In a mine of the character disclosed, in combination, a sterilizing circuit therefor, a tiring circuit therefor,- a normally charged condenser connectedto both said sterilizing circuit and said firing circuit, a rst discharge tube included in said sterilizing circuit and adapted to cause said condenser to discharge therethrough when the 'tube is red, a second ydischarge tube included in said firing circuit and adapted to cause said condenser to discharge therethrough as the second tube is tired, and electric contact actuating apparatus comprising a plurality of contacts adapted to be actuated by sound Waves and to control the firing of said rst andsecond discharge tubes selectively in accordance with the character of the sound 3. In an acoustic mine firing control system, a normal- Vly-inactive mine firing circuit, a sound responsive device ,tiring circuit when the charge on the condenser reaches a predetermined value.

4. In a mine of the character disclosed, in combination, electric contact actuating apparatus comprising a plurality of contacts adapted to be actuated by sound waves, a

12 sponsive device adapted to be set into operationV by sound signals transmitted-through the surrounding water, first and-'second pairs of contacts on said sound responsive device, saidtirst pair of contacts being adapted to vibrate when sound lsignals of a predetermined character are received =by the sound responsive device, a source of electrical energy connected to said Ifirst and second pairs of contacts, a first condenser connected to said first pair of contacts and adapted to becomecharged from said source as the contacts vibrate, a normally charged condenser,

electro-responsive detonating ymeans adapted to be operated by the'discharge current from said normally charged condenser, a first electron device having an anode thereof connected to said normally charged condenser and a control elernent thereof connected to said iirst condenser, said electron device being adapted to fire as the rst condenser becomes charged to a predetermined value'and to cause said normally charged condenser to discharge through said detonating means as the electron device is tired, said second pair of contacts being adapted to be operated when sound signals of a diierent character are received by the sound responsive device, and a second electron device having the anode thereof connected to said normally charged condenser and a control element thereof connected to said second pair of contacts, said second electron device being adapted to cause thenormally charged condenser to discharge through the second electron device when the second pair of contacts are operated.

`6..V In a mine of the character disclosed, a source of power, a condenser connected to said source of power and normally charged to the potential thereof, a discharge path forsaid condenser, an electro-responsive shipcounting device included in said path, and means including a sound responsive device and controlled by sound signals transmitted through an elastic medium lfor causing said condenser to discharge through said path when a predetermined interval of time has elapsed after the sound responsive device responds to the irst of said signals, thereby to operate said'shipcounting device.

7. In an acoustically controlled marine mine, -a normally ycharged condenser, a mine firing circuit including an electro-responsive detonating means and comprising -a -'irst discharge path lfor said condenser whereby said detonating means is operated as the condenser discharges through said path, a second discharge path for said condenser ada-pted to sterilize the mine for a predetermined period of time when the condenser is discharged therenormally inactive mine ring circuit, a condenser included in said'circuit, a 4source of power, circuit means including 'a'rirst pair ofcontacts included in said plurality of contacts and adapted to connect said condenser to saidsource of power intermittently in a manner to charge the con- 'denser therefrom. above a predetermined initial value as thev contacts are actuated in response to sound waves of a predetermined character, circuit means controlled by the charge on saidcondenser and adapted to activate said tiring circuit when the charge on the condenser reaches :a second predetermined value, a second pair-of contacts included in said plurality of contacts and adapted to be actuated yby sound wavesof a different character, and means controlled by said second pair of contacts and adapted to prevent an activationof said tiring circuit when signals of a different character are received.

5.\In a mine ofthe character disclosed, a sound rethrough, a sound rsponsive device adapted to be set into operation when sound signals are received thereby, circuit means including a plurality of contacts controlled by said sound responsive device, and means controlled by said contacts and adapted to cause said condenser to discharge through said first and second paths selectively in accordance with the character of signals received yby the sound responsive device.

8. In an acoustically controlled marine mine, a sound responsive device adapted to be set into operation in response to signals transmitted through the surrounding water, a source of energy, a plurality of discharge paths for said source of energy, detonating means included in one of said paths and' adapted to fire the mine as energy ilows in said one of the discharge paths, time measuring means controlled by said sound responsive device and Vadapted to cause energy to ow in said one of said dis- 9. In a mine of the character disclosed, the combination of a source of power, a condenser, means for charging said condenser to substantially the potential of said source of power, a discharge path for said condenser, an electron device included in said discharge path and adapted to cause said condenser to discharge as the electron device tires, counting means also arranged within said discharge path and adapted to be operated when said condenser discharges, a control element for said electron device, time measuring means operatively connected to said control element and adapted to lire the electron device when a predetermined period of time has been measured by the time measuring means, a sound responsive device for controlling the operation of said time measuring means in response to sound signals received from a vessel by the sound responsive device, and means for causing said condenser -to charge and discharge repeatedly after said counting means has been operated without additionally operating the counting means during the travel of the vessel past the mine.

10. In a mine of the character disclosed, a vibration responsive device adapted to be set into operation by sound waves or pulses of a predetermined character, an electron device, a normally charged condenser connected to said electron device and adapted to be discharged thereby when the electron device is tired, counting means adapted to he operated by the discharge current from said normally charged condenser, a control element for said electron device, a second condenser connected to said control element and adapted to lire said electron device when the second condenser is charged to a predetermined value, means including said vibration responsive device for charging said second condenser in response to continuous operation of the vibration responsive device, detonating means, and means included within said counting means for operatively connecting the detonating means to said normally charged condenser when the counting means has been operated a predetermined number of times whereby the detonator means is red by the discharge current of the normally charged condenser during the next succeeding discharge thereof.

11. A sterilizing circuit for an acoustic mine firing control circuit comprising a source of power, a normally charged condenser included in both said circuits, a discharge path for sm'd condenser, a trigger tube included in said path and adapted to discharge the condenser therethrough when the tube tires, said tube being extinguished as the condenser is discharged, a path-including said source of power for gradually charging the condenser to the normal charge thereof, a pair of normally open contacts for controlling the tiring of said tube, and means responsive to sound signals of a predetermined character for closing said pair of contacts.

12. In a vibrationally controlled underwater mine, a source of electrical power, a condenser, means for normally charging said condenser to substantially the potential of said source of power, two discharge circuits for said condenser, an electro-responsive detonating means included in one of said discharge circuits for firing the mine, a pair of electron discharge tubes in circuit with said condenser and adapted to control'the discharge of said condenser through said discharge circuits selectively in accordance with the tiring of the tubes, a vibration responsive devceradapted to be set into operation by vibrations transmitted through the surrounding water, and circuit means including a plurality of contacts controlled by said vibration responsive device for tiring said electron discharge tubes selectively in accordance with the character of vibrations received by the vibration responsive device.

13. y1n `a mine of the character disclosed, in combination, a vibration responsive device adapted to be set into operation as vibrations or pulsations are transmitted through the surrounding water, a' source of electrical power, a pair of discharge tubes connected to said source of power, a normally charged condenser connected to the anodes of said discharge tubes and adapted to be discharged through the tubes when the tubes are fired, and circuit means including a plurality of contacts controlled yby said vibration responsive means forring said discharge tubes selectively in accordance with the character of the vibrations received by the vibration responsive device.

References Cited in the file of this patent UNITED STATES PATENTS 1,310,568 Heap et al. July 22, 1919 1,491,004 Due Apr. 22, 1924 1,538,315 Due May 19, 1925 1,538,316 Due May 19, 1925 

